多体作用对氦原子团簇He_9压缩特性的贡献

MANY-BODY CONTRIBUTIONS FOR THE COMPRES-SIBILITY OF HELIUM ATOMIC CLUSTER

采用Ｌｏｗｄｉｎ方法计算了处于压缩状态的氦原子团簇Ｈｅ＿９体心立方向型的排斥势及其多体分量，并由此计算出团簇微观压强及其多体分压强。结果发现，多体作用对氦原子团簇Ｈｅ＿９压缩特性贡献较大。在相同体积下，由两体近似方法计算的体系压强比多原子体系实际压强偏高１０％～３０％；考虑三体分压强修正后，近似理论的计算值又会偏低１．５％～１０％；只有同时考虑三体、四体修正后，近似理论计算值与实际多原子体系的压强值基本一致。团簇Ｈｅ＿９所表现出的压缩特性与固态氦的实验结果相符合。

Lowdin scheme was applied to calculate the repulsive potentials and their multi-body expansions of compressed atomic cluster He_9.The micro-pressure and their expansions werecalculated. The results show that many-body effects are important for the compressibility ofatomic cluster He_9.At the same volume,the pressure calculated by two-body approximation is10%～30% higher than the actual many-body system. If three-body corrections are considered,the results become 1.5%～10%lower.When the four-body effect was included,the approxi-mation calculations fit real system quite well.The compression properties of atomic cluster He_9are similiar to the experimental results of solid helium.